Avulsion Fractures of the Ankle

Original Editors - Niels Verbeeck

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Definition/Description

An avulsion fracture is where a fragment of bone is pulled away at the ligamentous or tendinous attachment. It can be caused by a traumatic traction (repetitive long-term or a single high impact traumatic traction) of the ligament or tendon. This occurs as tendons can bear more load than the bone.

An avulsion fracture can occur at numerous sites in the body, but some areas are more sensitive to these types of fractures than others, such as at the ankle which mostly occur at the lateral aspect of medial malleolus or in the foot where avulsion fractures are commonly at the base of the fifth metatarsal, but also at the talus and calcaneus. A twisting injury to the ankle and foot may cause an avulsion fracture at any of these locations.

Clinically Relevant Anatomy

Taking the example of avulsion fractures at the 5th metatarsal; The metatarsal is divided into 3 parts: the tuberosity), the metaphysis and the head. Peroneus brevis attaches at the lateral side of the tuberosity (red area at figure), with peroneus tertius attaching at the dorsal side of the most proximal compartment of the metaphysis. Due to the high traction forces by these structures, tuberosity avulsion fractures commonly occur in an inversion injury (between the red and purple areas)

figure1: source: http://www.med-info.nl/images/images_trauma/Trauma_voet_MT5_Jones_groot.jpg

Characteristics/Clinical Presentation

The characteristics of an avulsion fracture differ from those of a ligament rupture. Unlike non-operative treatment of a lateral ligament rupture, non-operative treatment of avulsion fractures do not yield satisfactory results. Symptoms of an ankle avulsion fracture are very similar to an ankle sprain and it is very difficult to diiferentiate without an X-ray or an MRI scan.

Pain is usually felt in the ankle immediately post injury with an immediate onset of swelling. Bruising may develop and the patient will have difficulty walking or weight bearing on the ankle. If an avulsion fracture is present, there will be immediate pain over the outside aspect of the foot. and associated with significant swelling and localised tenderness over 5th metatarsal. History of the injury will be similar to that of an ankle sprain (plantarflexor inversion).

Differential Diagnosis

• A Jones fracture occurs as a result of a stress fracture to the 5th metatarsal, due to repetitive loading of the outside part of the foot from the patient’s underlying foot pattern or lower extremity alignment. Unlike a Dancer’s fracture a Jones fracture may not heal and often requires surgery.
• Stress fractures
• Mid-shaft fractures
  

Diagnostic Procedures

An X-ray may be ordered by the surgeon. Avulsion fractures are sometimes overlooked or when the injury to the 5th metatarsal occurs together with an ankle sprain. Other imaging methods are recommended, such as MRI, CT or scintigrams.

Outcome Measures

Good predictors of outcome are a splint made plaster and periods of no weight bearing (NWB). The evaluation of this happens with using Olerud ankle score, with linear analogue scales (LAS) for pain and comfort, and with questions about cosmesis and wearing of shoes. Gender, age, and fracture type did not affect outcome. The pain scale ranged from 0 (no pain) to 10 (the worst pain one could imagine), and the comfort scale also ranged from 0 (the least possible comfort) to 10 (perfect comfort).

add links to outcome measures here (also see Outcome Measures Database)

Examination

During the medical history taking the surgeon or a physiotherapist has to ask the patient how the injury occurred and when the pain started. Using the Ottawa Ankle Rules localize the exact area of pain. Palpation of the 5th metatarsal tuberosity is painfull.

Medical Management

Patients with an avulsion fracture of the base of the 5th metatarsal are usually treated conservative. If the bone is not displaced, the treatment is accomplished with a walking boot or a walking cast. They will be casted for four to six weeks. Surgery is only recommended if the bone is displaced from its normal position or when there is more than 30% of the cubometatarsal joint involved. The bone will be removed or fixed with osteosynthesis material. Crutches may be useful to avoid weight on the injured foot.

Physical Therapy Management

Avulsion fractures are often treated as ankle sprains. A physiotherapist doesn’t treat ‘an avulsion fracture’ on its own, but the dysfunctional movement and impairments of an individual. Therefore it is important to individualize the treatment.

It is important to follow a full ankle rehabilitation after an avulsion fracture, because inappropriately managed avulsion fractures can lead to significant long-term functional disability. Most fractures heal well, but following a strict immobilization it is indicated to regain full range of motion (normal arthrokinematics), strength of the lower extremity muscles, proprioception and functionality in sport.

A full ankle rehabilitation after an avulsion fracture consists of three phases, the acute phase, the recovery phase and the functional phase:

1. The first phase, also called ‘the acute phase’, can be started at two weeks postoperatively. The first phase will include passive range of motion exercises and crytherapy. This phase is based on the reduction of pain, inflammation and edema while retarding muscle atrophy of the lower extremity complex.
2. The second phase, also called ‘the recovery phase’,can be started after the patient has met the goals of the first phase.
   We can divide the rehabilitation program in 3 phases:
   - During the first 2 weeks: we will start with active range of motion exercises for the toes and the MPT joints, strengthening exercises for the ankle and foot are still too early. By the second week, isometric exercises to the dorsiflexors, plantar flexors, invertors and evertors of the foot are started. Active ankle movements are begun.
   - After 2 weeks: By week 6-8, we can start with active and passive range of motion exercises fot the ankle and the subtalar joint. Isometric and isotonic exercises for the ankle and subtalar joint are advised. Exercises improving lower extremity strength with theraband and proprioception exercises with a biomechanical ankle platform system. At the beginning of the second phase, advice the patients they should use the least resistant band. Toward the end of the second phase, the patient should begin using a wobble board to improve proprioception and begin closed kinetic chain activities (walking and loading).
   - After 8-12 weeks: strengthening exercises to the dorsiflexors, plantarflexors, invertors, evertors, long flexors and extensors of the toes. Full weight-bearing exercises may be permitted.
   
3. The third phase, also called ‘the functional phase’, can be started at six to eight weeks postoperatively. The third phase involves increasing power of the lower extremity complex, increasing neuromuscular control and utilizing sport-specific training of the lower extremity for a full return to sport.
   

Resources

Articles:

• E.W. Zwitser *, R.S. Breederveld, Fractures of the fifth metatarsal; diagnosis and treatment, Injury, Int. J. Care Injured 41 (2010) 555–562 (level: A1)
• Haraguchi N, Toga H, Shiba N, Kato F, Avulsion fracture of the lateral ankle ligament complex in severe inversion injury: incidence and clinical outcome, Am J Sports Med. 2007 Jul;35(7):1144-52 (level: A2)
• Peter Vorlat , Wim Achtergael , Patrick Haentjens, Predictors of outcome of non-displaced fractures of the base of the fifth metatarsal, International Orthopaedics (SICOT) (2007) 31: 5–10 (level: B)
• Duke G. Pao, Theodore E. Keats, Robert G. Dussault, Avulsion Fracture of the Base of the Fifth Metatarsal Not Seen on Conventional Radiography of the Foot: The Need for an Additional Projection, AJR 2000;175:549–552 (level: C)
  

Books:

• David F. Paton. Fractures and Orthopaedics. Edinburgh: Churchill Livingstone, 1988.
• Ronald McRace. Practical Fracture Treatment. 3rd ed. Edinburgh: Churchill Livingstone, 1994.

Sites:

• http://orthopedics.about.com/od/brokenbones/a/avulsion.htm
• http://www.foothealthfacts.org/footankleinfo/fifth-metatarsal_fractures.htm
• http://www.podiatrytoday.com/article/6565
• http://www.epainassist.com/sports-injuries/ankle-injuries/ankle-avulsion-fracture-symptoms-causes-treatment